Electric clock and the like



Aug. 12, 1930. F, POOLE 1,772,555

ELECTRIC CLOCK AND THE LIKE Filed Feb. 26. 1927 4 Sheets-Sheet. 1

Arrow 5Y5.

Aug. 12, 1930. PQOLE 1,772,556

ELECTRIC CLOCK AND THE LIKE 4 Sheets-Sheet 2 Filed Feb. 26, 1927 Aug. 12, 1930. F. POOLE 1,772,556

ELECTRIC CLOCK AND THE LIKE Filed Feb. 26, 1927 4 Sheets-Sheet 3 L." w... 7/ M J0 //v leg/ 2R.

Aug. 12, F POOLE ELECTRIC CLOCK AND THE LIKE 4 Sheets-Sheet 4 Filed Feb. 26, 1927 ATT'ORNEKfi.

Patented Aug. 12, 1930 UNITED STATES PATENT OFFICE ARTHUR I. .POOLE, OF ITHACA, NEW YORK, ASSIGNOB TO POOLE MANUFACTURING COMPANY, INC., A CORPORATION OF NEW YORK ELECTRIC CLOCK AND THE LIKE Application filed February 26,1927. Serial No. 171,162.

My invention relates to clocks and speedometers, and is designed especially for use on automobiles where trouble has been experienced with clock mechanisms, due to the fact that the jar of the automobile interfered with the running of the clock. While in the preferred embodiment of my invention hereinafter described I have shown it applied to an automobile, I do not wish to limit myself to this use, since my invention will be of value when used in connection with other devices. The subject matter of this application was divided out from my prior application upon which United States Patent No. 1,531,026 was granted on March 24, 1925. However, this application was filed after said patent was issued and is therefore not a divisional appli cation.

One of the objects of my invention is to provide an improved clock movement which will not be subject to the interruption by stopping and further, by taking advantage of I features peculiar to my hereinafter described clock, to combine with this clock means for the indication of speed. By the use of this combination, I am enabled to provide for an automobile a combined clock and speedome ter head which will be reliable and accurate.

A further object of my invention is the provision of a novel means of actuating the clock movement. I may use a vibrating member, such as a balance wheel vibrating under the influence of a spring, and I maintainv this balance in vibration by novel electrical means. The balance is kept in vibration by the expedient of displacing the free end of the hair spring through a small distance at each vibration of the balance. This action slightly winds this hair spring at each vibration of the balance and thus restores to the balance energy lost by friction.

In the preferred embodiment of my inventionthe power necessary to rewind the hair spring at each vibration of the balance wheel is arnished b an electric batter In the embodiment o my invention hereinafter described, this battery may be the customarybattery on automobiles used for starting, lighting, and other purposes.

A further object of my invention is to supply the power necessary to actuate the clock hands, so that this power will be entirely independent of the power necessary to keep the balance wheel in vibration. Consequently, any reasonable load may be put on the hands without interfering with the timekeeping qualities' of the clock. In this connection, my improved clock mechanism will be found of great value in cases where it is desired to run a paper record for the purpose of keeping record of the speed of the car or for other purposes.

A further object of my invention is to take advantage of the above described property of my improved clock mechanism and utilize the clock mechanism for one of the elements of my improved speedometer.

A further object of my invention is to provide an improved electrical circuit for actuating the clock mechanism to the end of entirely suppressing all sparking at the contact points.

Further objects of my invention will hereinafter be described and will appear to those skilled in the art from the following specifications and claims.

My invention' can be best understood by reference to the accompanying drawings, of which Figure 1 is a vertical cross section of the apparatus; Figure 2 is a section along the line of 2-2 of Figure 1; Figure 3 is a lon tudinal section along'the line of 3-3 of Figure 1; Figure 4 is a section along the line of 4-4 of Figure 1; Figure 5 is a circuit diagram; Figure 6 is a perspective of the complete device; Figures7, 8, and 9 are views of the speed indicating mechanism, showing successive positions assumed by this mechanism during operation of the device; Figure 10 is a vertical cross section of the mechanism shown in Figures 7, 8, and 9, looking'along line 1010 of Figure 7. The same reference numerals apply to the same parts in all of the figures.

Referring now to the figures, I have mounted my apparatus in a drawn casing 20 which is provided with'a glass cover 21 serving to shield a dial 22, over which moves the speed indicating hand 23 and a pair of clock hands 24 and 25. The dial 22 is provided with a series of speed graduations 26, and a clock dial 27. The casing 20 is mounted on the dash board of the automobile and the motion of the front wheels of the automobile, or of the transmission thereof, is transmitted through a flexible shaft (not shown) to a terminal 28, which rotates in a nut 29, which screws on to a stud 30 mounted in the casing. The terminal 28 is provided with a keyway in which fits a key 32 on the end of shaft 33, which is revolubly mounted in a bearing 34 mounted in the casing 20.

Referring now to Figure 6, which will be seen with a worm wheel 35 mounted on the end of the shaft 33 and is in mesh with a mating wheel 36, which is rotatably mounted on a stud 37 rigid in the framework of the machine, (Fig. 10).

The function of the train of mechanism first described is to rotate the wheel 36 at a rate which is proportional to the speed of the automobile. Conse uently, if the s eed of rotation of the whee 36 is measure the speed of the automobile ma be determined. The stud 37 is provided with a small stud 38. A spider 39, held in a normal position by a sprin 40 and having a pin 41 mounted therein an adapted to contact with a stop 42 rigid to the frame is rotatably mounted on the stud 38. The spider 39 is rovided with a boss 43, contacting with whic is an arm 44 resting in a notch 45 in the pillar 46 rigid with the frame work. The arm 44 is held in its position by means of a rod 47 which is mounted in the frame work so that it can reciprocate and is held by compression of a spring 48 in a position determined b the contact of a colar 49, rigidly mounte to the rod 47, with the plate 50 which is rigid with the frame work. The second collar 51 is rigidly mounted on the rod 47 and serves to raise the arm 44 when the rod 47 is lifted, as will hereinafter be described.

From what has just now been described, it will be apparent'that as long as the arm 44 is in the position shown in Figure 10, the spider 39 will be ressed into contact with the wheel 36 and will revolve with it against the tension of the returning sprin 40. Therefore, if the rod 47 should be lifte (Fig. 10) the arm 44 will be withdrawn from contact with the boss 43. Consequently, the friction between the spider 39 and the wheel 36 will be removed and the spring 40 will return the spider 39 to its normal positon, determined by the contact of the pin 41 with the sto 42. As before noted, the rod 47 is raise periodically by means afterwards to be described, this rod being held in the osition shown in Fi are 10 for a certain period and then quickly e evated to the position shown in Figure 8 in which the arm 44 is shown out of contact with the boss 43. As soon as this elevation occurs, the

spider 39 will at once be returned to its normal position by the spring 40.

As so far described, the action of the mechanism is that during a period when the rod 47 is in the osition shown in Fi re 10, the spider 39 is in contact with the w eel 36 and is carried around with it. When the rod 47 is thrown to its alternate position, the spider 39 returns to its normal position. Consequently, during each cycle of operation, the spider 39 is carried through a distance which depends upon the speed of rotation of the wheel 36, which in turn depends on the speed of'the I automobile. Therefore the angular displacement of the spider 39 from its normal position will be a measure of the rate at which the automobile is traveling. I

I will now describe the means by which this displacement of the s ider 39 is communicated to the speed in icating hand 23.

A stud 52 is rigidly mounted in the plate 50, extending through this plate. Rotatably mounted on the lower end of stud 52 (Figure 10) is a disk 53 having a returning spring 54 mounted on it and a central boss 55 which contacts with a spring 56 mounted on the arm 44 and held in a normal position by contact with a fin r 57. When the arm 44 is in the position s own in Figure 10, the spring 54 will return the disk 53 until a pin 58, mounted rigidly therein, contacts with the pin 41 on the spider 39, since the function of the spring 56 is to press the disk 53 against the plate 50 and hold it in this position by friction. The disk 53 has also mounted on it a second pin 59, which is adapted to contact with an car 60 on a disk 61, which is rotatabl mounted on the upper end of the stud 52 eing held thereon by a head 62 on said stu The disk 61 is also provided with a returning spring 63 extending between said disk and a stud 64, mounted in the plate 50, and which also serves as a point of attachment for the spring 54. The pillar 46 has mounted thereon a spring which, when in its normal position, serves to press the disk 61 against the plate 50 and thereby maintain it against the tension of the spring 63. The u per part of the disk 61 is mounted on a s eeve .66 on which ismounted the speed indicating hand 23. The sprin 65 is normally out of contact with the col ar 49, but when the rod 47 is raised to its alternate position, the s ring 65 is lifted from the disk 61, leaving t e latter free to return under the influence of the spring 63. The, complete cycle of action of'parts from 37 to 65, inclusive, will be hereinafter described, su uent to the description of the clock mechanism.

The clock mechanism can be best understood by reference to the pars ective view in Figure 6. Referring to said gure, it will be, apparent that there is a balance wheel 67 mounted on a shaft 68 which vibrates in the framework under the influence of the-hair springs 69 and 70. The hair sprin 69 has one end attached to the framewor and is provided with the customary fork 71, which is adapted to be rotated in the framework by means of a regulating wheel 72, rigidly mounted in the framework and thereby changes the effective len h of the sprin 69. By this means the perio of vibration o the balance wheel 67 may be accurately regulated.

e free end of the hair spring 70 is attached to the spring 73, fastened to the arm 5, linounted on shaft 7 t e adapted to contact witha second contact point 7, mounted on the arm 74 but electrically insulated from it.

It is evident that the vibrating system, consrsting of the balance wheel 67 under the infiuence of the two springs 69 and 70, ma be kept in vibration b the expedient of slightly rocking the arm 4 about its shaft 75 in a period equal to the natural period of the vibration of the balance wheel. The efl'ect of this rocking is to wind and unwind the spring 70 at each vibration of the balance wheel and thereby keeping the balance wheel in vibration.

I will now describe the means which the rocking of the arm 74 is accomplis ed.

18 ma y serving to position shown in Figu the armature 78. For the purpose of vibrating the armature 78 at the proper times, I have provided an electromagnet 82 having two legs, both of which are number 82 in the drawings. The electrical circuits of this electrom et are peculiar and are best shown in figure 5, from which it will be a is difl'erential windings of the magnet are connected in parallel to a storage battery which may conveniently be the storage battery used for starting the automobile, furnishing electric current for ignition and the lighting system on the car. When the contacts 76 and 77 are together, the current flows throu h both windings of the magnet and, since t ese windings oppose each other, the magnet is not energized. However, if the contact points are parated, then one of the difl'erential windings, 84 is inactive and the magnet is energized by the active winding 83. From the above it follows that when the contact points 76 and 77 are together, the armature 78 is in the position shown in Fig-.

ure 5, and that as soon as these points are th opened, the armature 78 is attracted to the electromagnet, thus moving the arm 74 to its alternative position.

I will now describe how the above mechanism keeps the balance wheel 67 in vibration. sume the parts in their normal position as shown in Figure 1. The battery 85 is connected to the electric circuit. Immediately, the armature 78 is attracted and the arm 74 is rotated in a clockwise direction (Fi ure 6), thus giving the initial tension to t e hair spring 70, and it will be observed that this rotation of the arm 74 will maintain the contact oints 76 and 77 in their open position. he alance wheel now starts to turn, but wh neutral point of the s ring 70 has been reached, the momentum of the balance wheel will carry it a little farther and the tension of the spring 70 will cause the contact oints 76 and 77 to close. This will at once geenergize the magnet 82, the armature 78 will be drawn away b the retractile spring 80 and the arm 74 wi 1 be rotated in clockwise direction. It will be observed that this rotation of the arm 74 will maintain the contact points 76 and 77 in their closed position, thus maintaining the deenergizing of the electromagnet 82. U n the return vibration of the balance w eel 67, the spring 70 will be unwound, and the contact points 76 and 77 will again be 0 ned. Immediately, the armature 78 will attracted, thereby rotatin arm 74 in clockwise direction and impartm additional impulse to the balance ly reason of the a ove, the balance 77. It is ement consumes more current than would required by a single current which is made and broken. However, since the current is su plied from the storage battery of the car, w 1ch is being retrue that this arran charged, while the car is running, I do not consider this objection ment.

of any material moshed by the expedient of connectin the armature 78 b link 86 to a ever arm 87, rotatab on a shaft 88, which e framework. A the arm 87 in its is rotatably mounted in sprin 89 serves to hold norms position. Rigid with the arm 87 is a lever arm 90, having mounted on it a feeding pawl 91, held in contact with a wheel 92 by a spring 93 spring retracting pawl 94 serves to keep the wheel 92 from following the back stroke of the pawl 91. From the above it is obvious that reciprocation of the armature will result in a step by step rotation of the wheel 92 in the direction of the arrow.

The shaft 88 has a worm 95 mounted on it which engages a worm wheel 96 and by means of a second worm 97 mounted on a shaft 19 turns the worm 98 frictionally mounted on a shaft 99, upon which is mounted the clock hand 24. A set of gearing 100 is provided to give the proper motion to the hour hand 25.

In order to provide for the setting of the hands, I have mounted the worm wheel 9 frictionally on the shaft 99. Rigidly mounted on this shaft is a collar 101, provided with a compression spring 102, which serves to hold the wheel 98 against a collar 103, rigidly mounted on the shaft 99. A nut 104 is provided by means of which the hands may be geqt independently of the motion of the wheel The above mechanism serves to feed the wheel 92 step by step at each oscillation of the balance wheel and the gearin between the wheel 92 and the hand 24 is suc that the hand kee s correct time. As before noted, the period of vibration of the balance whee may be regulated by the regulating wheel 7 2.

It will be observed that the above described clock mechanism is unique in that the power moving the hands is wholly independent of the motion of the balance wheel, except as to period; that is, have to do an work, except the slight work of shifting the contact points 76 and 77. Consequently any reasona 67. The shaft 99 may be used, as before noted, to turn a paper feed for the object of showing a record of instruments of any kind.

I will now describe the means by which the rod 47, the reciprocity of which, as before noted, controls the action of the speedometer ortion of the apparatus.

The rod 47, as before noted, is arranged to reciprocate in the framework and is held by the spring 48 in the position shown in Figures 1 and 10. It is provided with a flexible ortion 105 which projects through a hole in t e armature 78 sition by a spring 106 which is attached to a lever 107, mounted on an arm 108 rotatably mounted on the shaft 88. The arm 108 is provided with a single tooth 109 rigidly attached thereto, which is actuated by the feeding pawl 91 and to this end I have provided for the fourth tooth of wheel 92 a deeper A deep notch 8 9, and 10.

l stant, the hand 23 has been the balance wheel does not and is held in normal ponotch. When the pawl 91 encounters the deep notch of the wheel 92, it sinks in the to engage the tooth 109 ri (1 arm 108. Consequently, at every ourt stroke of the armature the arm 108 is rocked on its axis and thus permits a spring mounted on the frame work and bearing against the rod 105 to displace said rod in a position to be engaged by a tripping piece 111, mounted on the under side of the armature 78. Consequently, at every fourth stroke of the armature 78, the rod 47 will be reciprocated and after such reciprocation will remain in its normal position for the next three strokes of said armature.

I will now describe how this periodic re ciprocation of the rod 47 actuates the sgeed indicating a paratus shown in Figuresv 8, tartin with the parts in their normal position as s own in Figures 1 and 10,

assume that the automobile has started. The wheel 36 commences its rotation, carrying with it the spider 39, which in turn, by means of the pin 41 contacting with the pin 58 carries with it the disk 53, which by means 0 the pin 59 contacting with the ear 60 advances the speed indicating hand 23. This action continues during three strokes of the armature 78, assuming that the apparatus started from the zero osition of the wheel 92. On the fourth stroll the rod 47 is suddenly lifted. At this indisplaced for a distance proportional to the speed of the car during the time required for the three previous strokes of the armature 78. When the rod 47 is lifted, the spider 39 is unclutched from the wheel 36 by the removal of the friction exerted by arm 34 and at once returns to its normal position under the influence of the spring 40. However, the disk 53 is held in its displaced position, since it is prevented from returning by the friction of the spring 56. Consequently, the disk 61, to which is attached the hand 23, remains in its displaced position and the displacement of said hand indicates the speed of the wheel 36, which is proportional to the speed of the car during the three strokes of the armature 78 n the fifth stroke of the armature 78, the rod 47 is suddently returned to its normal position. This results in re-engagement of the spider 39 with the wheel 36 and in the releasing of the disk 53, which returns under the influence of spring 54 until the pin 58 makes contact with the pin 41. The hand 23, therefore, is held in its displaced position by reason of the friction exerted by the spring which has been returned to its normal position. Assume that during the second period that the speed of the car is increased. The spider 39 will be carried in advance of its former position, thereby advancing the hand 23 and this advancement of the hand 23 will continue until the speed of the car has become statione of the armature 78,

ary, when no further advancement of the hand 23 will take place.

ow assume that the speed of the car has been decreased during one of the time periods measured lgylthe three strokes of the armathe disk 61, the hand 23 will at once be returned by the spring 63 to a sition determined by the position of the isk 53, which has been carried forward b the spider 39 and then held in its displaced position by the friction of spring 56. Consequently, the hand 23 will take up a position indicative of the decreased speed oithe car.

In general, the may be described as measuring the displace: ment of a reciprocating part period of time and transmitting this displacement to an indicating hand.

here remains to describe but one other feature of my invention, which is a means which I have provided of insuring the start of the balance wheel 67 from rest. This is accomplished by providing the balance wheel 67 with a starting pin 112, which is ada ted to be actuated by a spring 113, mounte on an arm 114, mounted on a shaft 115, rotatably mounted in the frame work. The shaft as on it a lever arm 116 connected by a lever 117 to an arm 118 exten ing through the armature 78. When the apparatus is at rest, the parts are in osition, as shown in Figure As soon as t e battery is started, as before described, the retractile spring 80 will be pulled up by the electroma net 82. This will rotate the shaft 115 in a c ockwise direction (Figure 1) and the spring 113 will give a blow to the starting pin 112, thereby starting the balance wheel 67 in vibration. Under normal 0 eration when the balance wheel is running, tlib spring 113 will not encounter the pin 112, since this pin is out of the way when t e arm 11 4 ispperated. The sprin wheel a ing an 77 Man departures and variations may be made fiom the precise mechanism herein de scribed without departing from the spirit of my invention.

claim as my invention 1. In anelectric clock the combination of a vibrating member, elastic means controllin the time of vibration of said member, an electrical through said member and operable to pendoically wind said elastic means in synchronism with vibrations of said vibrating member, and maintain said member in vibration.

In an electric clock, the combination with a vibrating member, elastic means deterthe time of vibration of said member,

means for periodically displacing said elastic means to thereby communicate impulses to said vibrating member, clock hands and a gear train connected therewith, and means controlled by the vibrating member for supplying power to drive the clock train independently of the amount of power applied to t e vibrating member.

3. In an electric clock, the combination with a vibrating member, elastic means determining the time of vibration of said member, means for periodically displacing said elastic means to thereby communicate impulses to said vibrating member, clock hands and a gear train connected therewith, and electrical means controlled b the vibrating member for actuating the cloc train.

In an electric clock, the combination of a vibrating member, elastic means determin ing the time of vibration of said member, electrical means to periodically wind said elastic member in synchronism with vibrations of said vibrating member, whereby the same is kept in vibration, clock hands and a gear train connected therewith, and electrically operated means controlled b the vibrating member for actuatin the cloc train.

5. In an electric cIock, the combination of a vibrating member, elastic means determining the time of vibration of said member, and electric means to eriodically Wind said elastic means, said e ectric means includin an electric circuit, a battery in said circuit, a differentially wound magnet having two windings opposing each other, the windings of the magnet being connected in parallel to the storage battery, an armature, and a switch operatively connected with the armature and arranged in said circuit so that when the switch is closed current flows through both of the windings of the magnet without energizing the same, and when the switch is opened current flows through only one of the magnet windin s and the magnet is energized, whereby spafiring at the switch contact points is prevented.

6. In an electric clock,the combination of a balance wheel, a hair spring determining the vibration of the balance wheel, electrical means to periodically wind said in synchronism with vibrations of the balance wheel, said electrical means including an elecmg a pin on the balance wheel, and a lever operatively connected with the armature and adapted to be moved thereby to engage the pin upon starting the battery.

7. In an electric clock, the combination of a balance wheel, a hair vibration wheel, said electrical means including an electric circuit, a batter in the circuit, an electromagnet in the circuit, an armature, an intermittently operated switch in the circuit operatively connected with said armature, and starting means for the balance wheel, including a pin on the balance Wheel, and a lever operatively connected with the armature and adapted to be moved thereby to engage the pin upon starting the battery.

8. In an electric clock, an oscillating balance element, a hair spring connected at one end to said element, a member for holding and displacing the free end of the hair spring to vary its tension, and means controlled by changes in tension of said spring for operating said member at instants so related to the positions of the balance element during its oscillations as to maintain said element in oscillation.

9. In an electric clock, an oscillating balance element, a hair spring connected at one end to said element, an anchorage member for the free end of the hair spring, adjustable to vary the tension of the spring, and electromagnetic means controlled by the tension of said spring caused by oscillations of said element for adjusting said anchorage member to vary the tension of said hair sprin at in stants so related to the positions of t e balance element during its oscillations as to maintain said element in oscillation.

10. In an electric clock, an oscillating balance element, a hair spring connected to said element and controlling its oscillations, electromagnetically controlled means for varying the tension of said spring, a controlling circuit for said last mentioned means, and contact means operable in synchronism with said element forchan ing the condition of said circuit and there y causing operations of said controlled means to vary the tension of said spring in a manner to maintain said element in operation.

11. In an electric clock, an oscillating balance element, a hair spring connected to said element and controlling its oscillations, electromagnetically controlled means for varying the tension of said spring, a controlling circuit for said last mentioned means, contact means operable in synchronism with said element for changing the condition of said circuit and thereby causing operations of said controlled means to vary the tension of said spring in a manner to maintain said element in operation, and time indicating devices operable in increments by said controlled means.

12. In an electric clock, an oscillating balance element, an elastic device connected to said element to control its period of oscillation, a device for varying the condition of said elastic device in a manner to maintain said element in oscillation, electromagnetic means controlled by variations in the tension in said elastic device occurring during oscillations of said element for actuating said varying device, and time indicating means operable by said means.

13. In an electric clock, an oscillating balance element, an elastic device connected to said element to cause it to oscillate at a regu lar rate, means including an electric circuit controlled by said element during its oscillations, for varying the action of said device on said element in a manner to maintain said element in oscillation, and time indicating means controlled by said first mentioned means.

14. In an electric clock, an oscillating balance element, a hair spring connected at one end to said element, an arm oscillatable about the axis of said element, a contact element carried by said arm, a contact device also carried by said arm movable in the direction of oscillation of said arm into and out of contact with said contact element and yieldingly and resiliently biased out of contact with said contact element, the other end of said spring being connected to said device, whereby the movement of said arm will vary the tension of said spring and tend to pull said contact device into or out of engagement with said contact element, an electric circuit controlled by said contact element and device, and electromagnetic means included in said circuit and operable upon said arm to oscillate it and through it vary the tension of said spring and thus maintain said balance element in oscillation.

15. In an electric clock, an oscillating balance element, a hair spring connected at one end to said element, an arm oscillatable about the axis of said element, a contact element carried by said arm, a contact device also carried by said arm movable in the direction of oscillation of said arm into and out of contact with said contact element and yieldingly and resiliently biased out of contact with said contact element, the other end of said spring being connected to said device, where y the movement of said arm will vary the tension of said spring and tend to pull said contact device into or out of engagement with said contact element, an electric circuit controlled by said contact element and device, electromagnetic means included in said circuit and operable upon said arm to oscillate it and through it vary the tension of said spring and thus maintain said balance element in oscillation, and time indicating devices operable in increments by said electromagnet.

16. In an electric; clock, an oscillating balance element, a hair spring connected at one end to said element, an arm oscillatable about the axis of said element, a contact element carried by said arm, a contact device also carried by said arm movable in the direction of oscillation of said arm into and out of contact with said contact element and yieldingly and resiliently biased out of contact with said contact element, the other end of said spring being connected to said device, whereby the movement of said arm will vary the tension of said spring and tend to pull said contact device into or out of engagement with said contact element, electric means including a circuit controlled by said contact device for oscillating the arm to'vary the tension of said spring and maintain said balance element in oscillation, and time indicating devices operable by said electric means.

17. In an electric clock,

d spring, and

means controlled by said contact mechanism for varying the tension of said spring in a manner to maintain said balance element in oscillation.

18. In an electric clock, an oscillating balance element, a hair spring connected to said element, a circuit controlling device connected to said spring for varying its tension to maintain said balance element in oscillation, and in turn also operated between open and closed position by changes in tension in said spring, and electromagnetic means controlled by said device for operating it in synchronized relation to the oscillations of said element to vary the tension of said spring.

19. In an electric clock, an oscillating balance element, a hair spring connected to said element to impart regularity to its oscillations, a member connected to said spring and operable to vary the tension of said spring and maintain said balance element in oscillation, and means controlled jointly by said spring and member during the oscillation of said element for causing oscillations of said member at intervals related to the oscillations of said element.

20. In an electric clock, an oscillating balance element, a spring connected at one end to said element, a circuit controller connected to the free end of said spring, a time indicating device, and electrically controlled means operated by said controller for driving said time device and varying the tension of said spring to maintain said balance eleance element, and means maintaining saidelement in oscillation and including contact members engaged and disengaged at intervals by the oscillation of said element, an electromagnet having equal but magnetically opposing coils, one of said coils being contmuously energized, an armature for said electromagnet and biased to retracted position, means connected to said armature for imparting impulses to said element for starting said element from and said contact members so as to be closed and opened b said contact members, whereby arcing at t e contact members as the electromagnet is made efi'ective and ineffective will prevented.

In an electric clock, an oscillating balance element, a hair spring connected to said element to impart regularity to its oscilla tions, a member connected to said spring and operable to vary the tension of said spring and maintain said balance element in 05611- member during the oscillation of said element for causing oscillations of said members at intervals related to the oscillations of said element.

thereof, electromagnetic means for varying the influence of the spring upon said element,

of said element electromagnetic the influence of ment and thereby maintain said element in oscillation.

thereof, electromagnetic means operable upon said spring to vary the force of the latter upon said element, a source of electrical energy, and circuit means including said electromagnetic means and said source of energy and rendered eflective automatically through the oscillations of said element for electromagnetic means in a manner to vary the action of said spring upon said element and thereby maintain said element in oscillation.

26. In an electric clock or the like, an oscillating balance wheel, a hair spring connected at one end to said balance wheel, electromagnetic means having an armature movsaid eel to vary the tension of said spring at each oscillation of the wheel and thereby maintain said element in oscillation.

27. In an electric clock or the like, a balance wheel, a hair spring connected to said wheel for securing regular oscillations of said wheel, a controlling member operative upon said s ring for varying its influence upon said w eel, and electromagnetic means controlled by the oscillations of said wheel for 10 operating said member in alternate directions to vary the influence of said sprin u on said wheel and thereby maintain sai w eel in oscillation. 28. In an electric clock or the like, an oscillating balance element, a hair spring connected at one end to said balance element, electromagnetic means having an armature movable between two positions and connected to the free end of said spring to tension the same varying amounts upon the oscillation of said armature, and means controlled from said balance wheel and including electric circuits and said electromagnetic means for rockin said armature in synehronism with said e ement to vary the tension of said sprin at each oscillation of the element and there y maintain said element in oscillation. In testimony to the foregoing I hereto sign my name.

so ARTHUR F. POOLE. 

